"Bob" is a divorced dad of a 5 year old boy, "Tom". Tom lives with his mother and also spends a lot of time with his grandma and great grandmother. Both Bob and his ex-wife work full-time and he only gets to see his son a couple of times a week. He usually keeps him every Saturday.
About a month ago, Bob decided to get a puppy (partly for his son and partly for himself). The puppy is a very cute, male Bluenose Pitbull. A couple of weeks later he also moved to a new apartment (bigger) hoping for his son to have his own room and feel more comfortable.
Bob had been looking forward to spending time with Tom at his new apartment this weekend. However, things didn't go so well.
At some point the puppy barked at Tom because he wanted to play and Tom started crying. Bob scolded the puppy a few times and the crying stopped temporarily. Bob tried to comfort Tom by explaining that this is how puppies talk but Tom was inconsolable and had apparently peed his pants. He didn't want to eat his food and insisted his dad took him home.
Long story short, Bob's weekend was a disaster, leaving him hopeless and overwhelmed. At some point he thought of getting rid of the puppy.
Currently, Bob needs some alone time and not to have to see Tom for a few weeks. According to Bob, Tom is being raised in an environment, where both the grandma and the great grandmother are too fearful in general and the mom is overprotective.
Bob doesn't want to give the puppy for adoption but at the same time wants to make Tom feel at home in his new apartment without constantly feeling so afraid and wanting to go home to his mom.
Clarification:
Bob needs some alone time to reevaluate his life, which seems out of balance at the moment, and think how to handle his son's fear of dogs and caring for a puppy. The puppy seems to need a lot of attention as well. He's only 4 months and keeps eating twigs, leaves and rocks when out on a walk. He rushes the puppy to the vet every time he throws up twigs or leaves and is afraid of the puppy dying. On top of that, he knows he can't spend enough time with his son and feels he can't influence his upbringing the way he would like to so enjoying the time he does get to spend with his son is really important.
Question
How can Bob help his son overcome his fear of dogs so that he feels comfortable spending time with his dad and staying over at his place?